Rachel Kavanaugh must hope that nobody ever succeeds in placing a moratorium on the production of Shakespeare. Were it to happen, she might have to rapidly rethink her career. Kavanaugh has spent much of the past seven years staging Shakespeare's comedies, earning herself a reputation as one of Britain's best young directors. The 33-year-old has two Shakespeares opening this month alone: a West End transfer for The Merry Wives of Windsor, which won sparkling reviews when it opened at the Swan in Stratford last year, and a new production of The Two Gentlemen of Verona at the Open Air in Regent's Park, the theatre that inspires her most magical work.

When Kavanaugh says, "I am never happier than when I'm directing a Shakespeare," she means it. In a sense, it has been her ambition since childhood. "My mother was an actress, so when I saw actors on stage I thought, 'I want to be a part of that.' I was quite an eccentric child: I would read Shakespeare in the garden and act out the parts. I did a lot of acting at school, too, but I wasn't good." It wasn't until she gofered on a Kenneth Branagh season, before university, that she "discovered that there was this other job". Suddenly, her acting days were over.

She thinks the reason so few people share her fascination is bad teaching; crucially, she was taught to read the plays aloud. Even now, the first thing she does before starting a play is read it aloud to herself, looking for surprises. Perhaps that is why her productions feel so fresh: at her best, she can make a play as overperformed as A Midsummer Night's Dream seem new. Even audiences who thought they didn't like Shakespeare have been converted by her work.

"I've had people come up to me after a performance and say, 'Did you change the words? Because I understood it.' Well, no - it was just clear. I don't think you have to be highly educated to enjoy Shakespeare: it wasn't written for an elitist audience, it was written for everybody. And if it's done in a way that tells the story without dumbing down, then everyone can enjoy it."

If Kavanaugh has a tic, it is period settings. For her it is a vital springboard for the story. "I did a production of Romeo and Juliet in Washington last year that I didn't set in a specific world and I don't think it worked," she says. "I feel more grounded setting things in an environment in which people can play off each other." For Two Gentlemen she has chosen the 1790s, a flamboyant period suited to her sense of the play's oddness. "It has a boy who is exiled and becomes king of the outlaws, and a girl locked in a tower saved by a boy who comes with a ladder under a cloak. This is an eccentric piece of writing, to say the least. I felt we needed a world in which those kind of things were allowed to happen, but in which the actors could still play big emotional truths. I'm very keen on realism in Shakespeare, less keen on naturalism."

She is particularly fond of the 1940s, largely because "it's a world most people can relate to - and it makes me laugh". Both her Merry Wives of Windsor and Much Ado About Nothing were set in the postwar years. "In those plays, Shakespeare shows women meeting men and finding some sort of common ground. To set that in the 1940s seems to me - 'accessible' is a dreadful word - fun."

You can see why Kavanaugh concentrates on the comedies (she has also directed As You Like It and Love's Labours Lost): she is a person who punctuates her speech with a gurgling laugh. It belies the seriousness of her approach, the care she takes to ensure that her settings and productions illuminate the play. Partly her choice of plays has been a matter of necessity: the Open Air Theatre, where she has done most of her Shakespeare, is a jolly amphitheatre surrounded by trees, ill-suited to the raw emotions of the tragedies. But she worries about the director's equivalent of typecasting. "It's interesting that the one Shakespeare I've been asked to do at Stratford is Merry Wives. There might be a bit of, 'Oh, she's a merry girl.' I was delighted to do it - but I would love to be asked to do Othello or King Lear."

Merry Wives was her second production for the Royal Shakespeare Company; before that she directed Alice in Wonderland as the 2001 Christmas show. This was at the height of the furore over Adrian Noble's plans for the company, and Kavanaugh couldn't help but be affected by the volatile atmosphere. Reviewers declared her production awful, and even Kavanaugh admits it was "curate's eggish". It probably didn't help that she disapproved of Noble's plans: she thinks the demolition of the Royal Shakespeare Theatre is "unnecessary, emotionally, practically and financially", and emphasises that a London home for the RSC is essential. But then, she thinks more possessively of the company than most: "It's what made me want to go into the theatre. I remember well seeing The Merchant of Venice at the Aldwych, the first RSC production I ever saw, and thinking I was in heaven. Then I went to Stratford and thought it was the best thing in the world. It's hard to disentangle that sentimental attachment."

In Kavanaugh, you feel, Michael Boyd has a natural successor any time he chooses to step down as the RSC's artistic director. In the meantime she is getting plenty of experience in how to run a big organisation as an associate director at Birmingham Rep. "I'm having my cake and eating it, in that I get to be consulted about the programming, I go to all the board meetings, but I'm completely freelance. So I have concrete knowledge of what it is to be an artistic director, without that final responsibility and that lack of freedom."

She also gets to extend her own repertoire: earlier this year she co-directed, with Jonathan Church, the David Hare trilogy. It made her realise how much she usually misses out on: when you're working on Shakespeare, you can't expect the playwright to pop into the rehearsal room for a chat. It is also rare for her to direct a play so close to her own life. She studied at Manchester University and was "very into politics, very active in the union, endlessly marching. It was really emotional and exciting to go back into that bit of history - especially with The Absence of War, because it's all about the 1992 election and that happened just after I left Manchester."

Perhaps most importantly, the plays were relevant: The Absence of War opened just as British troops were sent to Iraq. "We had people shouting out at the curtain call, asking for protests against the war. The collision between what we doing in the theatre and what was happening in the world outside was thrilling." It's not easy to do this with A Midsummer Night's Dream - yet Kavanaugh insists that any production must strive to inspire passion.

"The point must be to provoke, even if it's to provoke laughter; to engage a live audience in some kind of debate, even if it's only a debate of entertainment. It's hard, with Shakespeare's comedies, to make obvious statements. But they always resonate. I hope they're not just fun, although sometimes they're mostly fun."

She would like to expand further, take in Chekhov, Ibsen, Stoppard, even do some opera. But ultimately she is wedded to Shakespeare, and plans to direct all his plays. So how does she react when a moratorium is mentioned? "I have to try and control myself. Why would you deny yourself something that is so exciting and eccentric and life-enhancing and challenging? I think there are lots of things that are wrong with the way people are introduced to Shakespeare, and there are probably lots of productions of Shakespeare that I wouldn't like, but it seems a kind of madness to cut something out of our culture that is so fantastic." And then she laughs. "Also, it's what I like doing. Don't take it away from me!"

· The Two Gentlemen of Verona starts previewing at the Open Air Theatre, London NW1, tonight. Box office: 020-7486 2431. The Merry Wives of Windsor starts previewing at the Old Vic, London SE1, on Saturday. Box office: 0870 609 1110.